The effect of external ATP and related compounds on the electrical and mechanical activity of isolated pieces of taenia coli has been studied. ATP, AMP and adenosine caused a decrease in the spontaneous tone, a decrease in the frequency of spike discharge, and hyperpolarization. ATP was up to 100 times as potent an inhibitor of spontaneous activity as AMP or adenosine. GMP, guanosine and inosine had no effect. High K+ contractures were relaxed by the same compounds and adenine, which was the most potent. Here again GMP, guanosine and inosine had no effect. ATP, AMP and adenosine prevented or shortened the initial depolarization produced by acetylcholine and carbachol. Inorganic phosphate was liberated from ATP and AMP applied to the bathing solution. The hydrolysis was not significantly decreased by g‐strophanthin. p‐Hydroxy‐mercuribenzoate caused an initial excitation as well as g‐strophanthin but neither inhibited the relaxing effect of ATP. The effects of extracellularly applied ATP are consistent with the view that they are exerted through changes in membrane permeabilities and that some of these effects are brought about by the adenosine part of the molecule.
M. Effe cts of exposure to vehicle exhaust on health . Scand J Work En viron Health I3 (1987) 505-512. Exposure to combustion engine exhaust and its effect on crews of roll-on roll-off ships and car ferries and on bus garage staff were studied. The peak concentration s recorded for some of the substa nces stu died were as follows: total part iculate s (diesel only) 1.0 rng/rn" , benzene (diesel) 0.3 mg/rn ", form aldehyde (gasoline and diesel) 0.8 mg/rn ", and nitrogen dioxide (diesel) 1.2 mg/m'. The highest observed concentr ation of benzo(a)pyrene was 30 ng/m ' from gasoline and diesel exhau st. In an experimen tal study volunteers were exposed to diesel exhaust diluted with air to achieve a nitrogen dioxide concentration of 3.8 mg/m '. Pulmonary function was affected during a workday of occupational exposure to engine emissions, but it normalized after a few days with no exposure. The impa irment of pulmonary fu nction was judged to have no appreciable, adverse, short-term impact on individual work capacity. In the experimental exposure study, no effect on pulmonary function was observed. Analy ses of urinary mutagenicity and thioether excretion showed no sign of exposure to genotoxic compound s among the occupationall y exposed workers or among the subjects in the experimental st udy.
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